PTC thermistor overload protection systems have been known heretofore. For example, O. H. Kilner U.S. Pat. No. 3,794,950, dated Feb. 26, 1974, shows an overcurrent protection system and sensor used therewith of the PTC thermistor type. A heater supplied by motor current heats the PTC thermistor which, upon reaching its anomaly point of 120.degree. C., causes the voltage on a capacitor to reach a diode breakover value thereby to gate a thyristor and interrupt the motor power circuit. The PTC thermistor is draped by a first layer of insulation, an elongaged heater is looped over that, a second layer of insulation is draped over the heater and an elongated heat sink is wrapped over the second layer of insulation.